Individual monomer and dimer units of the highly reiterated cryptic satellite (called alpha-component) of African green monkey (Cercopithecus aethiops) were purified by molecular cloning and sequenced. The data indicate that the set of approximately 5 x 10 to the 6, 172 base pair long sequences comprising alpha-component include a large number of related but slightly divergent sequences. A group of monkey DNA segments about 17 kilobase pairs long and containing alpha-component sequences joined to other genomic DNA has been isolated from a library of green monkey DNA in lambda-bacteriophage. Analysis of these sequences indicates that (1) domains of variant monomer units are grouped together, (2) the tandem repeats of alpha-component can be interrupted by other DNA sequences, (3) at least two classes of distinct sequences frequently occur joined to alpha-component and that these sequences themselves occur on the order of 10 to the 3 to 10 to the 4 times in the genome. The alpha-component sequences present on a single isolated monkey chromosome represent a special subset of the total. The interspersed highly repeated 300 base pair long Alu family of sequences found by others in human DNA is conserved in African green monkey in sequence, dispersal and copy number.